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/* SPDX-License-Identifier: GPL-2.0-or-later */
/*
* SHA-256 optimized for x86_64
*
* Copyright 2025 Google LLC
*/
#include <asm/fpu/api.h>
#include <linux/static_call.h>
static __ro_after_init DEFINE_STATIC_KEY_FALSE(have_sha_ni);
DEFINE_STATIC_CALL(sha256_blocks_x86, sha256_blocks_generic);
#define DEFINE_X86_SHA256_FN(c_fn, asm_fn) \
asmlinkage void asm_fn(struct sha256_block_state *state, \
const u8 *data, size_t nblocks); \
static void c_fn(struct sha256_block_state *state, const u8 *data, \
size_t nblocks) \
{ \
if (likely(irq_fpu_usable())) { \
kernel_fpu_begin(); \
asm_fn(state, data, nblocks); \
kernel_fpu_end(); \
} else { \
sha256_blocks_generic(state, data, nblocks); \
} \
}
DEFINE_X86_SHA256_FN(sha256_blocks_ssse3, sha256_transform_ssse3);
DEFINE_X86_SHA256_FN(sha256_blocks_avx, sha256_transform_avx);
DEFINE_X86_SHA256_FN(sha256_blocks_avx2, sha256_transform_rorx);
DEFINE_X86_SHA256_FN(sha256_blocks_ni, sha256_ni_transform);
static void sha256_blocks(struct sha256_block_state *state,
const u8 *data, size_t nblocks)
{
static_call(sha256_blocks_x86)(state, data, nblocks);
}
static_assert(offsetof(struct __sha256_ctx, state) == 0);
static_assert(offsetof(struct __sha256_ctx, bytecount) == 32);
static_assert(offsetof(struct __sha256_ctx, buf) == 40);
asmlinkage void sha256_ni_finup2x(const struct __sha256_ctx *ctx,
const u8 *data1, const u8 *data2, int len,
u8 out1[SHA256_DIGEST_SIZE],
u8 out2[SHA256_DIGEST_SIZE]);
#define sha256_finup_2x_arch sha256_finup_2x_arch
static bool sha256_finup_2x_arch(const struct __sha256_ctx *ctx,
const u8 *data1, const u8 *data2, size_t len,
u8 out1[SHA256_DIGEST_SIZE],
u8 out2[SHA256_DIGEST_SIZE])
{
/*
* The assembly requires len >= SHA256_BLOCK_SIZE && len <= INT_MAX.
* Further limit len to 65536 to avoid spending too long with preemption
* disabled. (Of course, in practice len is nearly always 4096 anyway.)
*/
if (static_branch_likely(&have_sha_ni) && len >= SHA256_BLOCK_SIZE &&
len <= 65536 && likely(irq_fpu_usable())) {
kernel_fpu_begin();
sha256_ni_finup2x(ctx, data1, data2, len, out1, out2);
kernel_fpu_end();
kmsan_unpoison_memory(out1, SHA256_DIGEST_SIZE);
kmsan_unpoison_memory(out2, SHA256_DIGEST_SIZE);
return true;
}
return false;
}
static bool sha256_finup_2x_is_optimized_arch(void)
{
return static_key_enabled(&have_sha_ni);
}
#define sha256_mod_init_arch sha256_mod_init_arch
static void sha256_mod_init_arch(void)
{
if (boot_cpu_has(X86_FEATURE_SHA_NI)) {
static_call_update(sha256_blocks_x86, sha256_blocks_ni);
static_branch_enable(&have_sha_ni);
} else if (cpu_has_xfeatures(XFEATURE_MASK_SSE | XFEATURE_MASK_YMM,
NULL) &&
boot_cpu_has(X86_FEATURE_AVX)) {
if (boot_cpu_has(X86_FEATURE_AVX2) &&
boot_cpu_has(X86_FEATURE_BMI2))
static_call_update(sha256_blocks_x86,
sha256_blocks_avx2);
else
static_call_update(sha256_blocks_x86,
sha256_blocks_avx);
} else if (boot_cpu_has(X86_FEATURE_SSSE3)) {
static_call_update(sha256_blocks_x86, sha256_blocks_ssse3);
}
}
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